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Abstract:
Several studies have shown activation of visual association areas and even primary visual cortex with auditory tasks in early blind subjects. Blindness occurring later in life was associated with less cross-modal plasticity as compared to early blindness. We examined one late blind and 9 sighted musicians with absolute pitch (AP) performing a pitch memory task which was contrasted with a motor control task. In the pitch memory task subjects had to compare the last or second last tone with the first tone and made a decision whether these tones were same or different after a visual prompt (sighted subjects) or a tactile prompt (blind subject). The motor control task was a rest condition with alternating button presses after a visual (sighted) or tactile (blind) prompt. To avoid interference with the MR scanner noise, a sparse temporal sampling fMRI-method with a long TR (17 sec) was used. Additionally, we varied the stimulus-to-imaging delay over 7 seconds in a jitter-like fashion to explore the time course of brain activation. When compared with the sighted subjects, the blind subject showed significantly more activation of visual association areas bilaterally (Brodman areas 7, 18, 19), bilateral lingual gyrus, inferior/superior parietal areas and premotor areas. Sighted subjects activated more right primary auditory cortex and the cerebellum compared to the blind subject. Our results suggest the use of a different cortical network in a late blind musician with AP relying more on visual association areas to facilitate pitch categorization and identification in our pitch memory experiment.
to facilitate pitch categorization and identification in our pitch memory experiment.
